Tool and process for casting a shaped part for the production of a turbine blade

ABSTRACT

The present invention relates to a tool for casting a shaped part for the production of a turbine blade, with several tool blocks which, when assembled with positive engagement in a predetermined manner, form a cavity for the shaped part, into which cavity flowable material can be introduced by means of one or more access apertures. At least one of the tool blocks receives a rotatable or displaceable insert or inset which borders the cavity with a surface and which can be fixed in different positions and/or orientations of the tool blocks, so that different cavity geometries are formed in the different positions and/or orientations of the insert or inset. The tool makes possible a later change of the geometry of the shaped part, in particular of the attack angle, without having to manufacture new tool blocks for this purpose.

FIELD OF THE INVENTION

[0001] The present invention relates to a tool for casting a shaped partfor the production of a turbine blade, in which tool plural tool blocks,assembled with positive engagement in a predetermined manner, form forthe shaped part a cavity into which a flowable material, particularlywax, can be introduced by means of one or more access apertures. Theinvention furthermore relates to a process for the production of ashaped part for a turbine blade with such a tool.

BACKGROUND OF THE INVENTION

[0002] In the development of turbine blades, numerous tests andadjustments are to be performed in the different development stages,such as the development of casting, machining or manufacturing, and canaffect the original tool development. Just differences between theaerodynamic model calculations and the later real properties of thefinished system can make it necessary to prepare a new set of tools forthe production of the initial shaped parts.

[0003] In the production and development process of a turbine blade, theshape of the turbine blade which is correct for the requirements isfirst calculated as a three-dimensional model. Injection molding toolsare produced from this model, which make possible the casting of ashaped part with the calculated three-dimensional shape. These injectionmolding tools are as a rule assembled from several tool blocks, which,assembled with positive engagement in a predetermined manner, form acavity for the shaped part. Molten wax is injected under high pressurethrough one or more access apertures into the cavity formed. Theinjected wax hardens after cooling to a shaped part, having the shapepredetermined by the injection molding tools. The tool blocks are thenre-moved. A ceramic casting mold for the later precision casting of theturbine blade is produced in a known manner with the shaped partprepared in this manner.

[0004] The production of the tool blocks for the injection mold is veryexpensive, since they are as a rule made of steel and are to define theshape of the later turbine blade as precisely as possible. Furthermore,the positive closure between the individual tool blocks must achieve asufficient sealing effect against the wax injected under high pressure.

[0005] It is precisely the dimensioning and production of the first rowof inlet guide blades of the turbine sets very high requirements, sincethe flow path of the hot gases is very sensitively affected by thisfirst row. A minimum deviation of the attack angle of these guide bladesfrom an ideal value already leads to a clear pressure increase orpressure decrease in the gas turbine, and this can considerably affectthe efficiency. In the case of such an undesired deviation, a new shapedpart with a correspondingly changed attack angle therefore has to beproduced, and for this the production of a completely new injectionmolding tool is necessary. Furthermore, several additional tolerancesare to be considered during the whole production process, and likewisecan exert a substantial effect on the flow path of the hot gas. Asexamples, there may be mentioned in this connection, scatter in theprocessing of the casting, or deviations in coating thickness. Suchdeviations are not yet known in the initial dimensioning of the shapedpart, and can therefore likewise give rise afterwards to a change of thegeometry of the injection molding tools.

SUMMARY OF THE INVENTION

[0006] Starting from this state of the art, the invention has as itsobject to provide a tool and also a process for the production of ashaped part for a turbine blade, making it possible to accomplish aneasy change of the leading edge geometry or of the attack angle of theturbine blade without a complete new production of the injection moldingtool.

[0007] The tool according to the invention for casting a shaped part forthe production of a turbine blade is assembled from several tool blocks.These tool blocks, when assembled with positive engagement or pushedtogether in a predetermined manner, form a cavity for the shaped part,into which cavity a flowable material, such as, for example, molten wax,can be introduced through one or more access openings provided therefor.The present tool is distinguished in that at least one tool blockreceives a rotatable or displaceable insert or inset, which has onesurface bordering on the cavity and which can be fixed in differentpositions and/or orientations with respect to the tool block, so thatdifferent cavity geometries or cavity volumes are formed in thedifferent positions and/or orientations of the insert or inset.

[0008] The insert or inset here preferably consists of the samematerials as the tool blocks and can be inserted into these withpositive engagement. By means of the possibility of producing differentcavity geometries in the different positions and/or orientations of theinsert or inset, a later adaptation of the geometry of the shaped partcan be undertaken by renewed introduction or injection of the liquidmaterial into the cavity with a correspondingly changed position and/ororientation of the insert. A new production of the whole injectionmolding tool, i.e., the shaping inner surface of the respective toolblocks, is thereby no longer necessary. One or more inserts or insetscan of course be provided in one or more tool blocks, and can bearranged by the person skilled in the art corresponding to the intendedpossibility of adjustment or displacement. The inserts are then fixedwith a suitable fixing means in the desired position before filling withthe flowable material, so that their position and/or orientation nolonger changes during the filling and hardening process of the flowablematerial. The fixing of the one or more inserts preferably takes placeby means of securing pins which engage in correspondingly providedrecesses in the respective tool blocks. The securing pins are pushed inthrough corresponding apertures in the insert. The correspondingrecesses in the tool blocks are constituted, according to the desiredstep spacing at which displacement is possible, as a correspondinglyfine hole pattern.

[0009] The insert(s) is/are preferably embodied such that they determinethe surfaces of the shaped part to be produced, which determine orcontribute to the course of the hot gas path of the turbine blade. Aparticularly advantageous embodiment here relates to the arrangement oftwo inserts or insets in opposed tool blocks. The inserts or insets arehere constituted such that when assembled they form a cylindrical insertunit for the determination of the geometry of the blade. The insert unitassembled from the two inserts or insets is rotatable around itslongitudinal axis in the tool blocks and can be fixed in differentrotational positions. Different attack angles of the blade can beimplemented by different rotational positions of the insert unit.

[0010] Fixing possibilities are preferably provided at such spacingsthat the attack angle can be changed in angular steps of 0.25-0.5°. Inthis manner, a shaped part with an altered attack angle can be producedvery quickly, simply and without new construction of the tool blocks, ifduring further development it should transpire that the originallydesigned attack angle did not fulfill the requirements for the hot gaspath because of manufacturing tolerances.

[0011] Such an embodiment of the tool has the further advantage thatshaped parts can also be produced therewith for turbine blades ofdifferent plants without having to prepare a separate respective tool.For example, turbine blades for turbine plants with other flowproperties or other mass flows, as particularly arise with gas turbinesoperated with different fuel types, can be produced hereby with one andthe same tool.

[0012] For an adjustment of the parting lines in the tool on changingthe position and/or orientation of the insert, adapters can be present,which displace the parting lines and/or compensate for a possible playbetween the insert and the tool block. It is also conceivable here toalready provide corresponding, preferably wedge-shaped, interspacesbetween the inserts, into which the corresponding adapters can beinserted after the positioning of the inserts.

[0013] In a further possibility of embodiment of the present tool, aninsert which is displaceable along an axis is provided in a tool blockwhich substantially serves to define the shape of the blade platform andof the blade foot, the height of the blade platform being determined bythe displacement position of the said insert. The displacement axis herecorresponds to the z-direction, which on insertion of the later turbineblade corresponds to the radial direction.

[0014] In the production of the shaped part, the individual tool blocksare assembled, preferably pushed together, the insert(s) or inset(s) arebrought into a position and/or orientation with which the desiredgeometry of the cavity or of the later shaped part is produced, and arefixed in this position on the tool blocks. Molten wax is then injectedunder high pressure into the thus produced cavity, and is solidifiedthere by cooling. After solidification, the tool blocks with theassociated inserts or insets are separated from the hardened wax shapedpart. A separation of the inserts from the shaped part is facilitated bythe adapters already described.

[0015] The tool and also the accompanying process for injection moldinga shaped part for the production of a turbine blade is particularlysuitable for the adjustment of the attack angle of the blade of theturbine blade or for the adjustment of the height of the blade platformof the turbine blade. The tool offers particular advantages in cases inwhich a high number of adjustments have to be undertaken during thedevelopment of the turbine blade. The more adjustments are required, themore advantages the present process offers, since a new injectionmolding tool does not have to be produced for each adjustment. Theadjustments can instead be implemented by simple adjustment of theinsert within the tool.

[0016] The tool or the accompanying process principally relate to theproduction of shaped parts made of wax. It is, however, obvious to theperson skilled in the art that other meltable materials other than waxcan be used for the production of the shaped parts with the presenttool. Furthermore, the material of the tool blocks play no essentialpart for the invention, so that materials are available to the personskilled in the art for this, as required corresponding to the respectiveapplication. The external embodiment of the individual tool blocks canlikewise be undertaken here according to the known state of the art.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The invention is again briefly described hereinbelow using anembodiment example in connection with the accompanying drawings, withoutlimitation of the general concept of the invention.

[0018]FIG. 1 is a diagram showing an example of an injection moldingtool which is assembled from several tool blocks;

[0019]FIG. 2 is a diagram schematically showing the construction of aturbine blade; and

[0020]FIG. 3 is a diagram showing an example of the embodiment of aninset in a tool according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021]FIG. 1 shows an example of an injection molding tool for theproduction of shaped parts for turbine blades. The tool consists of abaseplate 15 on which the four tool blocks 1-4 are arranged. Thebaseplate and the tool blocks consist of a steel material. The toolblocks can be displaced in corresponding guides of the baseplate 15, ascan be seen from the Figure. The inner surfaces of these tool blocks 1-4are shaped such that after assembly they form a cavity which providesthe shape for the shaped part to be manufactured.

[0022] The individual tool blocks are in this example pushed together inthe respective guides so that with positive engagement they seal off thecavity from the exterior. A wax injection aperture 6 is in this exampleprovided in the baseplate 15, and the injected liquid wax reaches thecavity 5 by means of corresponding channels (shown dashed). The wax isinjected under high pressure here and is solidified by cooling in thecavity. The tool blocks 1-4 are then separated from the wax shaped partproduced in this manner. This separation takes place by pulling apartthe individual tool blocks in the guides. Corresponding handles 16 areprovided on the tool blocks for this purpose in the present example. Anarrangement of this kind is already known from the prior art, but canalso be used for the tool of the present invention, at least onebounding surface of the cavity 5 formed by the tool blocks 1-4 thenbeing formed by a surface of an insert or inset, not visible in thisillustration.

[0023] With such a tool, shaped parts for turbine blades aremanufactured, such as are seen in FIG. 2, for example. This FIG. 2 showsthe typical components of a turbine blade 10: the blade 11, a blade band13, as well as a platform 12. For the production of a shaped partconstructed in this manner, the inner surfaces of the tool blocks 1 and2 of FIG. 1 are embodied for determining the suction and pressure sideof the blade 11, the tool block 3 is embodied for determining the shapeof the blade platform 12, and the tool block 4 is embodied fordetermining the shape of the blade 13.

[0024] With a fixed present geometry of the inner surfaces of these toolblocks 1-4, no possibility exists of a subsequent adjustment of thegeometry, for example for the production of another attack angle of theblade. Such a possibility of adjustment is implemented with the toolaccording to the invention, which is shown in a possible variantembodiment in FIG. 3. FIG. 3 here shows only a portion of the tool withthe tool blocks 1 and 2 for determining the blade 11. The further toolblocks 3 and 4 corresponding to FIG. 1 are embodied as known from thestate of the art.

[0025] In contrast to the known tools of the prior art for theproduction of shaped parts for turbine blades, the present tool has inthis example two tool blocks 1 and 2, which respectively receive aninsert 7 or 8 with positive engagement. For this purpose, the innersurfaces of both the tool blocks 1 and 2 are correspondingly shaped. Onassembly of the two tool blocks with their inserts or insets 7 and 8, acylindrical insertion unit 9 is formed which is rotatable about itslongitudinal axis within the tool blocks 1, 2, as is indicated in FIG. 3by the arrow. The two inserts 7 and 8 here cooperatively form thegeometrical shape for the blade 11, i.e., their surfaces bounding thecavity 5 are shaped corresponding to the pressure and suction side ofthe blade.

[0026] Optional attack angles of the blade 11 with respect to theplatform 12 or to the blade band 13 can be produced by means of therotatability of the insertion unit 9. The insertion unit 9 is fixed inthe corresponding desired position with respect to the tool blocks 1 and2 by means of securing pins (not shown in the Figure). The tool blocks 1and 2 have a corresponding hole pattern for different settings for thispurpose.

[0027] In this embodiment example, furthermore, a substantiallywedge-shaped cavity is provided between the two inserts 7, 8 at thetransition to the tool blocks 1, 2; interchangeable adapters 16 can beinserted into the said wedge-shaped cavity. These adapters 14 facilitatethe dismantling of the individual tool blocks after the injectedmaterial has hardened.

[0028] The tool is embodied in a preferred embodiment such that theattack angle, i.e., the insert unit 9, can be rotated in steps of about0.25-0.5° through a maximum angle of 2-3°, and can be fixed. This issufficient for the development of a turbine blade, taking possible lateradjustment changes into consideration.

[0029] In the same manner, a corresponding insert can be provided in thetool block 3, this time displaceably embodied in the direction of theblocks 1 and 2, in order to be able to adjust the height of the platform12 of the shaped part. It goes without saying that other surfaces of theshaped part can also be changed or adjusted in this manner, if acorresponding movable insert is provided.

1. (Amended) A tool for casting a shaped part for production of aturbine blade, with several tool blocks which, when assembled withpositive engagement in a predetermined manner, form a cavity for theshaped part, into which cavity flowable material can be introduced bymeans of one or more access apertures, wherein at least one of the toolblocks receives a rotatable or displaceable insert or inset whichborders on the cavity with a surface and which can be fixed in differentpositions and/or orientations with respect to the at least one toolblock, so that different cavity geometries are formed in the differentpositions and/or orientations of the insert or of the inset. 2.(Amended) The tool according to claim 1, wherein the insert or insetdetermines or contributes to the hot gas geometry of the blade of theturbine blade.
 3. (Amended) The tool according to claim 1, wherein atleast two inserts or insets are constituted in opposed tool blocks, suchthat when assembled they form, for determining the geometry of theblade, a cylindrical insertion unit which is rotatable around itslongitudinal axis in the tool blocks for setting the attack angle of theblade and which can be fixed in different rotation positions. 4.(Amended) The tool according to claim 1, wherein the rotatable insert orinset can be fixed in rotation positions which respectively differ byabout 0.25-0.5°.
 5. (Amended) The tool according to claim 1, whereinthe, or a further, insert or inset is arranged to be displaceable alongan axis in a tool block which determines the geometry of the bladeplatform, such that in different displacement positions, differentheights of the blade platform are produced.
 6. (Amended) The toolaccording to claim 1, wherein adapters are provided which are insertableinto interspaces arising between the insert or inset and the tool blocksand/or between several inserts or insets.
 7. (Amended) The toolaccording to claim 1, wherein at least one insert or inset can be fixedin the different positions and/or orientations with respect to the toolblock by means of securing pins which engage in corresponding recessesin the tool block.
 8. (Amended) The tool according to claim 1, whereinthe tool blocks include, arranged on a baseplate, a tool block for thepressure side of the blade, a tool block for the suction side of theblade, a tool block for the blade platform, and a tool block for theblade band of the turbine blade.
 9. (Amended) A process for productionof a shaped part for a turbine blade, comprising the steps of:assembling several tool blocks with positive engagement for formation ofa cavity which gives the shape of the turbine blade; introducing liquidmaterial into the cavity and hardened in the cavity; removing the toolblocks; using at least one tool block which receives, before theintroduction of the liquid material, a rotatable or displaceable insertor inset which borders on the cavity with a surface, the insert or insetbeing fixed, before the introduction of the flowable material, in aposition and/or orientation with respect to the at least one tool blockin order to set the shape of the cavity with the selected positionand/or orientation.
 10. (Amended) The process according to claim 9,wherein the insert or inset is fixed in the selected position and/ororientation with respect to the tool block by means of securing pins.11. (Amended) The process according to claim 9, wherein, before theintroduction of the flowable material, adapters are inserted intointerspaces arising between the insert or inset and the tool blocksand/or between several inserts or insets.
 12. (Amended) The processaccording to claim 9 for the adjustment of the attack angle of the bladeof the turbine blade on the shaped part.
 13. (Amended) The processaccording to claim 9 for the adjustment of the height of the bladeplatform of the turbine blade on the shaped part.
 14. (New) A tool forcasting a shaped part for production of a turbine blade, comprising: aplurality of tool blocks which, when assembled with positive engagementin a predetermined manner, form a cavity for the shaped part into whichflowable material can be introduced by means of one or more accessapertures; wherein at least one of the tool blocks for receiving arotatable or displaceable insert or inset which borders on the cavitywith a surface and which can be fixed in different positions and/ororientations with respect to the at least one tool block, so thatdifferent cavity geometries are formed in the different positions and/ororientations of the insert or of the inset.